Apparatus for grinding drills and the like



Aug. 29, 1950 P. H. NEEDHAM 2,520,647

APPARATUS FOR GRINDING DRILLS AND THE LIKE Filed Nov. 28, 1947 I5Sheets-Sheet l INVENTOR.

P/WL H NEEDHAM Aug. 29, 1950 P. H. NEEDHAM APPARATUS FOR GRINDING DRILLSAND THE LIKE 3 Sheets-Sheet 2 Filed Nov. 28, 1947 INVENTOR. QWL H.NEEDHAM 3 Sheets-Sheet 3 Aug. 29, 1950 P. H. NEEDHAM APPARATUS FORGRINDING DRILLS AND THE LIKE Filed Nov. 28, 1947 R m m H H m w W H m J MA Q p M. E S 2 a7472 Z4 W a g a w 6 Patented Aug. 29, 1950 APPARATUS FORGRINDING DB ANn rHELIn 4 v Paul H. Needham, Beverly Hills, Calif.Aipplication November as, ie n's ri mo; 788,491

. This-invention relates to apparatus for grinding. the-points of toolsandi mplements, such as twistdrill's, having generally conical end facesf-which the coning angle mustbe accurately maintained at a determinedvalue and, in addition, a predetermined clearance must be accuratelyground from a reference line such as the V cuttingedge of a twist drill,back=toa rear area such as'the heel of a twist drill. In-the grinding ofdril1s,' it is desirable that'this clearance angle vary from the cuttingedge back to the heel, starting. with, e. g.'-three degrees at thecutting edgeand ending with, e. g; fifteen degrees at the heel. Itisalso necessary that the clearance be I the same for each lip-of thedrill 'and that the two cutting edges be exactlysymmetrical so that, inrotating, :they will describe the same conical surfaceofrevolutioni Theclearance angle at the cutting edge should be within the range fromtwo-to four degrees.

A general object of my'invention is to pro-" vide a mechanism by the useof which the several lips of a twist drill may be consecutively groundOn-theirend faces with identical coning angle and clearance, and withthe clearance varying gradually and uniformly from a predeterminedminimum angle at the cutting edgeto a predetermined maximum angle attheheel. Such gradual variation'of clearance angle produces a'clearance; which in cross section is curved graddurability.

.A furtheriobject of my invention is to provide anapparatus-rby theme,of which'the desired coning a'ngle'andclearance can be ground quicklyand expeditiously. A further object is to provide anapparatus which maybe used by a relativelyunskilled operatorto grind drill points toexactly the desired shape, ..To thisend, the invention provides an"apparatus which will. hold and guide a drill so that it: is practicallyimpossible for the drill to be improperly? ground, the only requirementbeing that the operator follow a few simple operative steps. v

In. order to attain a. clearance angle startin immediately at thecuttingedge; it is necessary tog-avoid rotating the ;drill through acomplete revolution while in contact with the grinding wheel.Accordingly, a further object of the in vention is to provide a grindingapparatus which may-beoperated so as to presentth'edrill-to thegrindingwheel with the cuttingedge in-exactly.

to then swingthe drillarcuately througha sum cient angle-to proceed fromthe initial clearance angle to the final clearanceangle whilecontinuously rotating the drill, shifting the line of contact from thecutting edge to the heel, and maintaining the proper coning angle, and,finally,

to Withdraw -the drill from the grinding wheeland "to-indexfl the drill'soas to bring the other lip of the drill-into position for a similaroper-' ually from .thecutting edge to the heelw This provides formaximum-cutting edge strength and l the-proper position for. thegrinding of the initial j clearance angle andthe proper. coming: angle,

Another object of the invention is to provide a 'nov'el and improvedquick acting chuck mechan'isn'i f or holding I the drill.

Other objects will become apparent -in the ensuing specifications andappended drawings in whichz i r Fig; I is a front viewof'a grindingmechanism embodying my invention; r

Fig. -2 is a' front endview, partially in section, ofthechuck'andindexing mechanism and associatedparts;-

"Fig. miss a secthnahiew Of a mod f ed for th a e;' 1

Fig. 3 is fan'end view-of the apparatus, with the base'portions thereofshown'in section as in dicated by the line 33-of -Eig. 1;

Fig.4 s a'diagrammatic end view ofthe grindj in'g wheel and drillindicating how the arcuate" relief angle is ,produced'bythe swinging ofthe drillabout' theai'zis of the' chuck arbor;

Fig.14a is anend lines of grinding;

Fig. 4b is a side view of the drill indicating'the j .crovvningffii e.,relief curvature) of thefend ur du i rin n Fig. 5*is' a perspective viewof the operating 7 Fig.1}; isfa transversie sectional view ofthei Fig. 9is a perspective view. of the "inner as smbly of the chuck;

Fig lQisanend view o f the assembly shown in Fig. 9; and

Fig.- ll'is a persp jaws.--p.

I .In the machine which is. shown herein as anillustrativeexample-ofone*form in which theinvention may be. embodied;a: grinding wheel 15 V is mount'cdi-for rotationinza hoodi IS which-issupported upon a base l1, and is provided with viewof .a' drill showingthe ctive view of. one of the chuck annular bead 53d'on the post. 53aso: as toxretain the post against axial 'movementin the :sleeve. Theother end of the. sleeve 53b is formed with a pair of ears .53e betweenwhich is hinged, on a pin 53f, a lug on the end of a universal couplingmember 56a. The member 56a. is pivotedyat 6|| on an axis at rightanglesto the hinge pin- 53 to .the arm 55.... .5

The fork 52'embraces" the arm 31' oftheyoke 36 and is connected :thereto:by; diametrically opposed pivots. |i|.'v The heel -62 of the-fork 52,where it joins the arbor 24', is provided with a lug 63 which isembraced by a pair of links 64,- pivoted thereto at 65. The links 64also embrace the bridging portion 66 of the yoke 36, which bridgingportion is provided with a longitudinally extending slot.6'|. A bolt.68extends through each of the arms 64 and the slot. 61 and has aheadedthumbnut 69 threaded upon its upper end; By' 5 tightening thethumbnut 69,- the links 64" may be clamped against the sides of thebridging portion 66 of the yoke 36 so as'tolocklthe yoke 36 in aselected position of adjustment. By loosening the thumb nut 69, theentire chuck and yoke assembly may be swung about the axis of the pivot6|, relative to the fork 52, therebyto'change the angle subtendedbetween the chuck:axis and the plane of the grinding wheel (and to varythe coning angle 0 of the drill point).

During the adjustment of the coningangle, the arms 54 and 55 mayseparate or move together in order to permit the chuck to be shiftedhorizonta11y,while maintaining the vertical level of the socket 56. a j1 The heel 62 of the fork 52 is provided with a lug which moves betweenthe extremities of a notch 1| in a stop member 12,.carried by thebearing 25.- The stop member 12 is, arched to conform to the curvatureof the outer surface of the bearing and is provided with a slot 13through which a screw 14 is threaded into .the bearing 25, to secure thestop member against the bearing. By loosening the screw" the stop member- 12 may be adjusted to selected positions,

within the limits provided by the slot". Thusthe limits of downwardswinging movementof the chuck can be varied. Ordinarily, such adjustmentwill be effected for the purpose ofsetof ,the angle is concerned.Thejheel 62 provides a shoulder 15 (Fig. '7) which bears against one endof the bearing 25. A washer 16, secured to the end of the arbor 24 by acap screw'll, bears against the other end of the bearing 25, to securelyhold the arbor against longitudinal movement. 7 1

Translatory movement of the arm 21 so as to move the chuck past theperiphery of the grinding wheel, is provided for, by a screw shaft 18which is mounted for rotation in bearings 19 on the base [.1 and whichis threaded through alug 6. attached: to the ring- 32 and projecting upwardly throughv a longitudinal slot 8| in the shaft 28. The lug80 alsofunctions as a. key, operating in theslotB ,to hold the ring 32 againstrotation. Theshaft 21.8 may be provided with suitable heads 82 at itsrespective ends, bearing against the hearing '|9-to hold the shaftagainst endwise movement, and with a1hand1e 83 by means of which theshaft to the ring 32 and from it may be rotated. Movement is transmittedfrom the ring 32 to the arm 21. 1 :In my. improved chuck mechanism, thejaws 40iare pivotedwithinthe' quill 39 by :means' of trunnions' 84and.85 on each jaw, pivotally'received in..bearings 86 in the quill 39.The trun-' nions 84 and 95 extend in the same direction so that 'a jawmay be inserted or removed fromthe quill'by endwise movement of the jaw;The trun-l nions 84, are located at one side of a jaw while thebitingedge 81 thereof is at the opposite sides of the. jaw. Consequently, thebiting edges'i8'l maysswing inwardly'toward the center ofthe quill,toengage the periphery of a drill or other tool inserted into. the chuck.The jaws are provided with fingers .88 which extend outwardly throughslots 89 in the quill and cooperate with operating rings 98 which arekeyed into the operating barrel 4| 'by means of cylindrical keys 92. Thekeys 92 are engaged in key slots in the peripheries of the rings 99, andin slots in the annular inner wall of the barrel 4|. Spacer rings 93 areinterposed between operating rings 98. The ring 93 at one end of thechuck is retainedby a rolled'edge on the peripheral wall oflthe barreland cooperates with an integral bottom 93" of the barrel to confine theother rings 93' and 90. 7

Each operating ring Sithas an internal cam face 94 of helical shape and,at the outer end thereof, a reentrant finger 95. The cam surfaces 94define cut out spaces in the rings 90, in which the respective levers 88are received, and extend through 360 degrees. I

In the operation of the chuck, rotation of the operating barrel 4| inthe counterclockwise direction as viewed in Fig. Swill cause the camsurfaces 94 to bear against the outer ends of the levers 88, moving theminwardly and causing the jaws to move" into clamping engagement with atool embraced therebetween. During such move-' ment, the'quill'39 may beheld against rotation by holding the handle 46,- 41 while it is latchedinto the collar 42. When it is desired to release the chuck, theoperating sleeve is rotated in the counterclockwise direction, and thejaws will be moved outwardly by the action of small mouse trapsprings 91encircling the trunnions 84 and bearing against-' the inner wall of thequill and against the jaws respectively. Movement of the operating ringin the opening direction is limited by engagement of the finger levers88. I

' In a drill grinding operation, adrill is first inserted into the chuckand the chuck fastened as described above, after it has been presentedto 95 against the the periphery -ofthe grinding wheel to determine itsproper location lengthwise of the chuck.

The chuck is then. rotated, with the shaft"- unlatchedfrom the quill,and the'handle 46in the raised position, until one of the cutting edgesof the drill is disposed substantially horizontally and in contact withthe periphery of thegrindin'g wheel." The arm .2! is then retracted andthe grinding wheel is rotated. The arm Z'l-is then advanced,:.whi1e. thehandle. is held. in the

